Hybrid transmission having synchronizers

ABSTRACT

A transmission used in a hybrid vehicle comprising a planetary gear set and a synchronizer. The planetary gear set having a plurality of members and the synchronizer coupling and decoupling one of the members to change a speed ratio in the transmission.

FIELD OF THE INVENTION

The present invention relates generally to transmissions, and moreparticularly to transmissions used in hybrid vehicles.

BACKGROUND OF THE INVENTION

Hybrid vehicles commonly use at least two different energy conversionprocesses that can include a mechanical engine and an electric motor.And the associated transmission, or whether a transmission is used atall, sometimes depends on the particular drive configuration of thehybrid vehicle—parallel, serial, or mixed. One example of a transmissionthat can be used in a mixed hybrid is an electrically variabletransmission (EVT).

EVT transmissions typically have at least one planetary gear set wherethe mechanical engine and the electric motor are operably connected todifferent members of the planetary gear sets. Further, wet clutches areused to change speed ratios in the transmission, and hydraulic systemsare in turn used to control the wet clutches. Hydraulic systems arecomplex, costly, and require many components including the particularlybulky and difficult to manufacture valve bodies.

SUMMARY OF THE INVENTION

One implementation of a presently preferred transmission that is used ina hybrid vehicle comprises at least one planetary gear set with aplurality of members, and at least one synchronizer that selectivelycouples and decouples at least one of the plurality of members to changea speed ratio in the transmission.

Another implementation of a presently preferred transmission that isused in a hybrid vehicle comprises an input shaft, an output shaft, afirst planetary gear set, a second planetary gear set, a third planetarygear set, a first electric motor, a second electric motor, and at leastone synchronizer. The first planetary gear set is operatively connectedto the input shaft, the second planetary gear set is operativelyconnected to the first planetary gear set, and the third planetary gearset is operatively connected to the second planetary gear set. Further,the first electric motor is operatively connected to both the first andsecond planetary gear sets, and the second electric motor is operativelyconnected to both the second and third planetary gear sets. Lastly, thesynchronizer can be actuated and deactuated to change a speed ratio inthe transmission.

Another implementation of a presently preferred transmission that isused in a hybrid vehicle comprises an input shaft, an output shaft, afirst planetary gear set, a second planetary gear set, a third planetarygear set, a first electric motor, a second electric motor, a firstsynchronizer, a second synchronizer, and a third synchronizer.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of the presentinvention will be apparent from the following detailed description ofthe preferred embodiments and best mode, appended claims andaccompanying drawings in which:

-   -   FIG. 1 is a schematic of the general configuration of an        embodiment of a transmission used in a hybrid vehicle;

FIG. 2 is an enlarged view of a synchronizer shown in the transmissionof FIG. 1;

FIG. 3 is a graph showing different component speeds on the y-axisversus vehicle speed on the x-axis for the transmission of FIG. 1, asthe transmission changes speed ratios; and

FIG. 4 is a chart showing the status of each synchronizer at thedifferent operating modes of the transmission of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring in more detail to the drawings, FIG. 1 shows an exemplaryconfiguration of a transmission 10 used in a hybrid vehicle (not shown)that does not require wet clutches to change speed ratios in thetransmission. The hybrid vehicle itself can include, among othercomponents, a mechanical engine 12 that sends torque to the transmission10 one or more batteries 14 that store electrical power, one or morepower inverters 16 that deliver electrical power, and variouscontrollers (not shown) that control components in the transmission. Themechanical engine 12 can be an internal combustion engine, a dieselengine, or the like, that can for example emit torque at about aconstant 2,000 revolutions per minute (rpm) throughout transmissionoperating modes. The battery 14 can be used to store and dispenseelectrical power to electric motors. The battery can be a high voltageDC battery, or any other device that can likewise store and dispenseelectrical power. The power inverter 16 delivers that stored electricalpower to electric motors and also enables the battery 14 to store powerduring regenerative braking. And the various controllers can include amotor controller (not shown) for an electric motor.

The transmission 10 can be of any type suitable for use in hybridvehicles that receive torque from the mechanical engine 12 and deliverthat torque to wheels (not shown) of the vehicle; in particular, thetransmission 10 can be the two-mode type. The transmission 10 has atleast one planetary gear set to provide a mechanical advantage, and atleast one synchronizer to help provide that mechanical advantage. Thetransmission 10 can further include at least one electric motor that cangive torque to the transmission, several shafts that can carry torque,and a housing 18 to provide structure to the transmission and that canbe in the form of a transmission case or supports. The abovetransmission components, and others, take the transmission throughvarious operating modes to change speed ratios. And many of thesecomponents are “operatively connected or joined” to one another, meaningthat they emit or drive torque to one another either directly, as whenthe components physically touch each other, or indirectly, as when thecomponents are connected through one or more other components.

As mentioned, a planetary gear set is used in the transmission 10 togive the transmission any one of numerous known mechanical advantages.For instance, the planetary gear set can include several membersthat—depending on a particular condition, i.e., whether the particularmember is driving, driven, or held stationary—can provide a speedincrease with a torque decrease, a speed decrease with a torqueincrease, a direct drive, a reverse drive, and others. Each conditioncan constitute a different operating mode with its own speed ratios,output torques, and output speeds.

Particular to this embodiment, a first planetary gear set 26 can includea sun gear 28, a plurality of planet gears 30 that are meshed with thesun gear 28 and disposed on a carrier 32, and a ring gear 34 that ismeshed with the planet gears 30. Likewise, a second planetary gear set36 can include a sun gear 38, a plurality of planet gears 40 that aremeshed with the sun gear 38 and disposed on a carrier 42, and a ringgear 44 that is meshed with the planet gears 40. And a third planetarygear set 46 can include a sun gear 48, a plurality of planet gears 50that are meshed with the sun gear 48 and disposed on a carrier 52, and aring gear 54 that is meshed with the planet gears 50. As between theseplanetary gear sets, the sun gear 28 can be operatively joined to thering gear 44 through a hub plate gear 86, and the sun gear 38 can beoperatively connected to the sun gear 48 through a second sleeve shaft62.

The several shafts generally carry torque through the transmission 10from the mechanical engine 12 to drive the hybrid vehicle. An inputshaft 20 receives torque from the mechanical engine 12 and sends thattorque to other transmission components. The input shaft can be drivendirectly by the mechanical engine or indirectly through a torquetransfer device (not shown). The torque transfer device can beincorporated between the mechanical engine 12 and the input shaft 20 toprovide a selective torque-dampened connection between the mechanicalengine and the input shaft. At its other end, the input shaft 20 isoperatively connected to a planetary gear set; specifically, the inputshaft 20 can be operatively connected or directly connected to the ringgear 34.

An intermediate shaft 22 can also be included. The intermediate shaft 22can operatively join one planetary gear set to another planetary gearset, and can be selectively operatively connected to one more planetarygear set. Specifically, the intermediate shaft 22 can operatively jointhe carrier 32 to the carrier 42. In this way, the intermediate shaftcan carry torque between these planetary gear sets.

An output shaft 24 can be further included that receives torque fromother transmission components and sends it eventually to the drivewheels. To do this, the output shaft 24 is operatively connected to thecarrier 52 of the third planetary gear set 46.

Also mentioned, an electric motor can be used in the transmission 10that can set as a motor or a generator in a particular operating mode.For example, the electric motor can give torque to, or drive, one ormore planetary gear sets, provide a braking function, and cansubstantially synchronize the speeds of different transmissioncomponents. The term “substantially synchronize” can mean bringing therelative rotation speed of each different transmission component withina particular range, for example with a +/− 50 rpm range, so that thecomponents can eventually engage each other at about the same speed.

Still referring to FIG. 1, a first electric motor 56, or generator, canbe incorporated between the first planetary gear 26 and the secondplanetary gear set 36. The first motor 56 can be operatively connectedto, and thus can drive, a member on each of the first and second sets bya first sleeve shaft 58. Specifically, the first electric motor 56 canbe operatively connected to the sun gear 28 and the ring gear 44.

Similarly, a second electric motor 60, or generator, can be incorporatedbetween the second planetary gear set 36 and the third planetary gearset 46. The second electric motor 60 can be operatively connected to,and thus can drive, a member on each of the second and third planetarygear sets by the second sleeve shaft 62. Specifically, the secondelectric motor 60 can be operatively connected to the sun gear 38 andthe sun gear 48.

A synchronizer is used in the transmission 10 to smoothly engage tworotating transmission components so that they rotate at the same speedwhile avoiding a transmission bump, or noticeable impulse load during anoperating mode change. The synchronizer can be selectively actuated ordeactuated to couple/decouple or ground/unground the particulartransmission component when the transmission changes operating modes. Ingeneral, synchronizers will be known to those of ordinary skill in theart, and suitable synchronizers can include those used in manualtransmissions or in transfer cases.

In this embodiment, a first synchronizer 64 is disposed the thirdplanetary gear set 46, specifically adjacent the ring gear 54 so thatthe first synchronizer can ground the ring gear to the transmissionhousing 18 when actuated, and unground the ring gear from the housingwhen deactuated. Referring to FIG. 2, the first synchronizer 64 is adouble cone synchronizer, but it could be a single or triple conesynchronizer depending partly on the thermal load it will endure. Thefirst synchronizer 64 can have, among other components, a sleeve 66, ahub 68, and one or more cones or rings 70, 72, and 74. The sleeve 66 hasan external groove 76 for receiving a shift fork 78 which can be carriedby a shift rail 80 that both can direct the sleeve's movement. The shiftfork and rail can be controlled by a controller (not shown) to actuateand deactuate the synchronizer. The hub 68 can be splined to atransmission component, or in this case, attached to the transmissionhousing 18. And the cones or rings 70, 72, and 74 can provide variouscontact and friction surfaces during synchronization. The aboveconstruction and functionality are similar for a second synchronizer 82and a third synchronizer 84.

The second synchronizer 82 is disposed adjacent the third planetary gearset 46, specifically adjacent the carrier 52 so that the secondsynchronizer can couple the carrier to the intermediate shaft 22 whenactuated, and decouple the carrier from the intermediate shaft whendeactuated. The second synchronizer 82 is also a double conesynchronizer that can have a sleeve, a hub, and one or more cones orrings. A controller similarly controls a shift fork and a shift rail.

The third synchronizer 84 is disposed adjacent the second planetary gearset 36, specifically adjacent the ring gear 44 so that the thirdsynchronizer can ground the ring gear to the transmission housing 18when actuated, and unground the ring gear from the housing whendeactuated. The third synchronizer 84 can further couple the ring gear44 to the second sleeve shaft 62 when actuated, and decouple the ringgear from the second sleeve shaft when deactuated. The thirdsynchronizer 84 is also a double cone synchronizer that can have asleeve, a hub, and one or more cones or rings. A controller similarlycontrols a shift fork and a shift rail.

FIG. 1 is only a schematic of the configuration of the transmission 10,and as such does not show the physical packaging of the transmission.But in general, the transmission can be packaged so that the input shaft20, the intermediate shaft 22, and the output shaft 24 are generallyaligned along an axis constituting the center axis of the transmission.Also, the first, second, and third planetary gear acts 26, 36, and 46can be all coaxially arranged about the intermediate shaft 22; as canthe first and second electric motors 56 and 60. Further, the first andsecond electric motors can circumscribe, or partly surround the first,second, and third planetary gear sets. And the first and second sleeveshafts 58 and 62 can circumscribe the intermediate shaft 22.

Referring to FIGS. 3 and 4, the transmission 10 can be dynamicallyshifted through several operating modes including a low EVT mode with a1^(st) mode and a 2^(nd) mode, a high EVT mode with a 3^(rd) mode and a4^(th) mode, and a reverse mode. In general, the operating modes can becontrolled by various devices, sources, signals and the like. Forexample, an ECU (not shown) can be used to monitor various operatingconditions —including speed resolvers 88, 90 to monitor the respectiveelectric motor speeds, and speeds sensors 92, 94 to monitor therespective input and output shaft speeds—and respond by controllingcertain transmission components, like the synchronizers, to put thetransmission in a particular operating mode. In each mode, asynchronizer can be actuated or deactuated to provide different speedratios, output torques, and output speeds.

As mentioned, the transmission 10 can be of the two-mode type. Thismeans that the transmission first goes through a low range, and then ahigh range. In the low range, the transmission 10 can operate in the lowEVT mode with the first synchronizer 64 continually actuated “on” (S1)when the transmission shifts in the 1^(st) and 2^(nd) modes. And in thehigh range, the transmission 10 can operate in the high EVT mode withthe second synchronizer 82 continuously actuated on (S2) when thetransmission shifts in the 3^(rd) and 4^(th) modes.

For example, the transmission 10 can start in the low EVT mode to movethe vehicle. Here, the transmission can have two operating options, bothwhere the first synchronizer 64 can be actuated on (S1) to ground thering gear 54. In option one, the second electric motor 60 (EM2) canalone drive the third planetary gear set 46 independent of the firstelectric motor 56 (EM1) and the mechanical engine 12 (ME). Or in optiontwo, the second electric motor 60 can drive the third planetary gear set46 in one direction to move the vehicle, while the first electric motor56 can run in an opposite direction and then the mechanical engine 12can also run. In either option, the electric motors can substantiallysynchronize the speed of the ring gear 44 with that of the second sleeveshaft 62 so that the third synchronizer 84 can be actuated on (S4) tocouple the ring gear 44 to the second sleeve shaft 62. The transmission10 is then shifted in the 1^(st) mode.

Still in the low EVT mode, the electric motors can substantiallysynchronize the speed of the carrier 52 with that of the intermediateshaft 22 so that the second synchronizer 82 can be actuated on (S2) tocouple the carrier 52 to the intermediate shaft 22. Also, the thirdsynchronizer 84 (S4) can be deactuated to decouple the ring gear 44 fromthe second sleeve shaft 62. The transmission 10 is then shifted in the2^(nd) mode.

In the high range, the transmission 10 can operate in the high EVT mode.The electric motors can substantially synchronize the speed of the ringgear 44 with that of the second sleeve shaft 62 so that the thirdsynchronizer 84 can be actuated on (S4) to couple the ring gear 44 tothe second sleeve shaft 62. Also, the first synchronizer 64 can bedeactuated to unground the ring gear 54, and, as mentioned, the secondsynchronizer 82 can be actuated on (S2). The transmission 10 is thenshifted in the 3^(rd) mode.

Still in the high EVT mode, the third synchronizer 84 (S4) can bedeactuated to decouple the ring gear 44 from the second sleeve shaft 62.Also, the electric motors can slow the speed of the ring gear 44 so thatthe third synchronizer 84 can be actuated on (S3) to ground the ringgear 44, and the second synchronizer 84 can be actuated on (S3) toground the ring gear 44 so that the third synchronizer 82 can beactuated on (S2). The transmission 10 is then shifted in the 4^(th)mode.

To shift in the reverse mode, the first synchronizer 64 can be actuatedon (S1) to ground the ring gear 54, and the second electric motor 60 canrotate in a direction opposite of the direction it rotates when thevehicle moves forward. Further operating modes can include an enginestart-stop mode and an electric mode, both where the first synchronizer64 can be actuated on (S1).

Indeed, the graph of FIG. 3 shows that while the transmission isdynamically shifting through the 1^(st), 2^(nd), 3^(rd), and 4^(th)operating modes, the mechanical engine speed (ME) can remain generallyconstant and the vehicle output speed gradually increases.

While certain preferred embodiments have been shown and described,persons of ordinary skill in this art will readily recognize that thepreceding description has been set forth in terms of description ratherthan limitation, and that various modifications and substitutions can bemade without departing from the spirit and scope of the invention. Theinvention is defined by the following claims.

1. A transmission used in a hybrid vehicle, comprising: at least oneplanetary gear set including a plurality of members; and at least onesynchronizer to selectively couple and decouple at least one of theplurality of members to change a speed ratio in the transmission.
 2. Thetransmission of claim 1 further comprising: an input shaft receivingtorque from a mechanical engine of the hybrid vehicle and sending torqueto the at least one planetary gear set; at least one electric motoroperatively connected to at least one of the plurality of members andbeing capable of substantially synchronizing the speed of the at leastone of the plurality of members with the speed of a transmissioncomponent; and an output shaft receiving torque at least partly from theat least one planetary gear set and sending torque to drive the hybridvehicle.
 3. The transmission of claim 2 further comprising a firstplanetary gear set operatively connected to the input shaft, a secondplanetary gear set operatively connected to the first planetary gearset, and a third planetary gear set operatively connected to the secondplanetary gear set, wherein each of the planetary gear sets include asun gear, a plurality of planet gears meshed with the sun gear anddisposed on a carrier, and a ring gear meshed with the planet gears. 4.The transmission of claim 3 further comprising a first electric motoroperatively connected to and being capable of at least partly drivingboth the first and second planetary gear sets, and a second electricmotor operatively connected to and being capable of at least partlydriving both the second and third planetary gear sets, wherein the firstelectric motor is operatively connected to the sun gear of the firstplanetary gear set and to the ring gear of the second planetary gearset, both through a first sleeve shaft, and wherein the second electricmotor is operatively connected to the sun gear of the second planetarygear set and to the sun gear of the third planetary gear set, boththrough a second sleeve shaft.
 5. The transmission of claim 4 whereinthe input shaft is operatively connected to the ring gear of the firstplanetary gear set, the sun gear of the first planetary gear set isoperatively joined to the ring gear of the second planetary gear setthrough a hub plate gear, the sun gear of the second planetary gear setis operatively connected to the sun gear of the third planetary gear setthrough the second sleeve shaft, the carrier of the third planetary gearset is operatively connected to the output shaft, the carrier of thefirst planetary gear set is operatively joined to the carrier of thesecond planetary gear set through an intermediate shaft, and theintermediate shaft is selectively operatively connected to the carrierof the third planetary gear set.
 6. The transmission of claim 5 furthercomprising a first synchronizer disposed adjacent the ring gear of thethird planetary gear set to selectively ground and unground the ringgear to a transmission housing to change a speed ratio in thetransmission.
 7. The transmission of claim 6 further comprising a secondsynchronizer disposed adjacent the carrier of the third planetary gearset to selectively couple and decouple the carrier to an intermediateshaft to change a speed ratio in the transmission.
 8. The transmissionof claim 7 further comprising a third synchronizer disposed adjacent thering gear of the second planetary gear set to selectively ground andunground the ring gear to a transmission housing, or couple and decouplethe ring gear to a second sleeve shaft, both to change a speed ratio inthe transmission.
 9. The transmission of claim 1 wherein the at leastone synchronizer selectively grounds and ungrounds at least one of theplurality of members to a transmission housing to change a speed ratioin the transmission.
 10. The transmission of claim 1 wherein the atleast one synchronizer selectively couples and decouples at least one ofthe plurality of members to an intermediate shaft to change a speedratio in the transmission.
 11. The transmission of claim 1 wherein theat least one synchronizer selectively grounds and ungrounds at least oneof the plurality of members to a transmission housing, or couples anddecouples at least one of the plurality of members to a second sleeveshaft, both to change a speed ratio in the transmission.
 12. Atransmission used in a hybrid vehicle, comprising: an input shaft thatreceives torque from a mechanical engine of the hybrid vehicle; a firstplanetary gear set operatively connected to the input shaft, a secondplanetary gear set operatively connected to the first planetary gearset, and a third planetary gear set operatively connected to the secondplanetary gear set; a first electric motor operatively connected to andbeing capable of at least partly driving both the first and secondplanetary gear sets, and a second electric motor operatively connectedto and being capable of at least partly driving both the second andthird planetary gear sets; at least one synchronizer that can beactuated and deactuated to change a speed ratio in the transmission; andan output shaft that sends torque from the transmission to drive thehybrid vehicle.
 13. The transmission of claim 12 wherein each of thefirst, second, and third planetary gear sets include a sun gear, aplurality of planet gears meshed with the sun gear and disposed on acarrier, and a ring gear meshed with the planet gears.
 14. Thetransmission of claim 13 wherein the first electric motor is operativelyconnected to the sun gear of the first planetary gear set and to thering gear of the second planetary gear set, both through a first sleeveshaft, and wherein the second electric motor is operatively connected tothe sun gear of the second planetary gear set and to the sun gear of thethird planetary gear set, both through a second sleeve shaft.
 15. Thetransmission of claim 14 wherein the input shaft is operativelyconnected to the ring gear of the first planetary gear set, the sun gearof the first planetary gear set is operatively joined to the ring gearof the second planetary gear set through a hub plate gear, the sun gearof the second planetary gear set is operatively connected to the sungear of the third planetary gear set through the second sleeve shaft,the carrier of the third planetary gear set is operatively connected tothe output shaft, the carrier of the first planetary gear set isoperatively joined to the carrier of the second planetary gear setthrough an intermediate shaft, and the intermediate shaft is selectivelyoperatively connected to the carrier of the third planetary gear set.16. The transmission of claim 15 wherein the first, second, and thirdplanetary gear sets and the first and second electric motors are allcoaxially arranged about the intermediate shaft, and wherein the firstand second electric motors both circumscribe the first, second, andthird planetary gear sets, and further wherein the first and secondsleeve shafts circumscribe the intermediate shaft.
 17. The transmissionof claim 12 wherein the first or the second electric motor is used tosubstantially synchronize the speeds of one member of one of theplanetary gear sets with another member of another of the planetary gearsets before those two members are coupled by the at least onesynchronizer to change a speed ratio in the transmission.
 18. Thetransmission of claim 13 wherein the at least one synchronizer isdisposed adjacent the ring gear of the third planetary gear set toselectively ground and unground the ring gear to a transmission housingto change a speed ratio in the transmission.
 19. The transmission ofclaim 13 wherein the at least one synchronizer is disposed adjacent thecarrier of the third planetary gear set to selectively couple anddecouple the carrier to an intermediate shaft to change a speed ratio inthe transmission.
 20. The transmission of claim 13 wherein the at leastone synchronizer is disposed adjacent the ring gear of the secondplanetary gear set to selectively ground and unground the ring gear to atransmission housing, or couple and decouple the ring gear to a secondsleeve shaft, both to change a speed ratio in the transmission.
 21. Atransmission used in a hybrid vehicle, comprising: an input shaft thatreceives torque from a mechanical engine of the hybrid vehicle; a firstplanetary gear set operatively connected to the input shaft, a secondplanetary gear set operatively connected to the first planetary gearset, and a third planetary gear set operatively connected to the secondplanetary gear set; a first electric motor operatively connected to boththe first and second planetary gear sets, and a second electric motoroperatively connected to both the second and third planetary gear sets;a first synchronizer that can be actuated and deactuated to selectivelyground and unground a member of the third planetary gear set; a secondsynchronizer that can be actuated and deactuated to selectively coupleand decouple a member of the third planetary gear set; a thirdsynchronizer that can be actuated and deactuated to selectively groundand unground a member of the second planetary gear set, or couple anddecouple the member of the second planetary gear set; and an outputshaft that sends torque from the transmission to drive the hybridvehicle.